7

Suppose I upload a picture taken from a digital camera onto SE... is my privacy protected and is all EXIF data scrubbed from StackExchange?

5

Easy to test, I just uploaded a small picture taken with my phone, and ran exiv2 on it:

File name       : sample.jpg
File size       : 23428 Bytes
MIME type       : image/jpeg
Image size      : 204 x 153
Camera make     : SAMSUNG
Camera model    : GT-I9300
...

Then I uploaded it here:

uploaded sample

The md5sum differs, and the file does not seem contain any Exif data:

File name       : XRiYI.jpg
File size       : 6509 Bytes
MIME type       : image/jpeg
Image size      : 153 x 204
XRiYI.jpg: No Exif data found in the file

See also the help pages of Imgur, the service used by SE:

The maximum file size limits vary based on type of user. For all users the maximum non-animated file size you can upload is 20MB. The image is then compressed down to a smaller size based on the user type.

Conclusion: Exif data is stripped after upload, this saves space for the image host. There is no need to worry about the metadata, but beware when uploading pictures of yourself being drunk or neighborhood.

1
5

Yes, it appears so. At least basic tools find no EXIF data, I haven't dug in with specialized forensic tools. The image is also recompressed.

$ exif IMG_20131019_163230.jpg  # the original image (taken by my phone camera)
EXIF tags in 'IMG_20131019_163230.jpg' ('Intel' byte order):
--------------------+----------------------------------------------------------
Tag                 |Value
--------------------+----------------------------------------------------------
Image Width         |2560
Image Length        |1920
…
Name of GPS processi|11 bytes undefined data
GPS date            |2013:10:19
--------------------+----------------------------------------------------------
EXIF data contains a thumbnail (8149 bytes).
$ exif 8Na8r.jpg # uploaded via the “Add image” button
Corrupt data
The data provided does not follow the specification.
ExifLoader: The data supplied does not seem to contain EXIF data.
$ exiftime 8Na8r.jpg
8Na8r.jpg: couldn't find Exif data

enter image description here

1
  • Interesting. Wonder if it's being watermarked. Also doesn't mean Imgur does not record the EXIF data somewhere. Nov 4 '13 at 13:30

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